What puts you at risk for heart attack? Is it high blood pressure? Poor diet and lack of exercise? Or maybe high cholesterol? The answer can be any or all of these, but that’s not the whole story. Half of all heart attack victims have normal cholesterol levels…their heart attack was the first sign that something was wrong. Now there is a test that can tell you not only the standard total cholesterol, LDL, HDL and triglyceride levels…but the number of LDL and HDL particles and how big the particles are. Why is that information important? How can that knowledge affect the determination of risk?

First, let’s review some basic information about cholesterol. About 75% of the cholesterol in your blood is made in your liver and other assorted cells. The other 25% comes from the food you eat. Cholesterol is only found in animal products. Your body uses the cholesterol to produce hormones and several vitamins. Cholesterol doesn’t dissolve readily in water, so not much can be transported by the blood. For this, your body relies on lipoproteins to move cholesterol and triglyceride particles to where they need to go. Triglycerides travel on the inside of the particle, cholesterol sticks to the outside. Low density lipoproteins (LDL) have lots of cholesterol and very little protein in them. LDL lipoproteins are the major carriers of cholesterol in the blood. When there is a lot of cholesterol in the cells, the receptors are blocked which leaves the LDL circulating in the blood. The LDL is oxidized and taken up by macrophages which then swell and stick to the arterial walls, forming plaque. Plaque takes up valuable room in the artery, making it harder for blood to go through. This raises blood pressure and can eventually cause a heart attack by blocking an artery completely. High density lipoproteins have a lot of protein, so not much room for cholesterol; therefore they have less chance of depositing plaque on the arterial walls. HDL particles contain cholesterol that is not easily oxidized. It is thought that they “scour” the arterial walls and clean out excess cholesterol. The cholesterol that was removed from the walls is then transported back to the liver where it is processed and can do no harm. Triglycerides are chains of high-energy fatty acids that provide much of the energy your cells need to function.

In assessing cardiac risk, you need to know how much cholesterol a person has (we’ll call cholesterol particles “passengers”), how many lipoprotein particles a person has (“vehicles”), and how big the lipoprotein particles are (“busses vs. compact cars”). Now, if your arteries are the roads, the best scenario would be a small number of large vehicles to keep traffic flowing smoothly. Imagine 150 people (number of particles) being transported down a road (in the artery) - you could fit all the people into 3 busses (large particles) and traffic would be very manageable or you could have 150 little cars (small particles) vying for space slowing everyone down. It would also be prudent to take a closer look at the size and number of LDL particles vs. HDL particles.

The NMR LipoProfile test will report the traditional lipid panel with the addition of number and size of particles. Those readings are then used to determine insulin resistance and diabetes risk. One of the earliest signs of impending insulin resistance is alteration of lipoprotein metabolism. All these results combined with family history can help your physician create a much more effective treatment plan.